The chemiluminescent lighting system to which the present invention relates is prepared by mixing two liquid components which are kept separate until light is desired. At the desired time, the two liquid components are mixed and chemical light is produced. Typically, the first component is an oxalate component dissolved in a suitable solvent, while the second component is typically a peroxide compound dissolved in a suitable solvent. Usually the first component includes a fluorescer to heighten the chemiluminescence of the system, and the second component usually includes a catalyst to eliminate the induction period before light is produced upon mixing the two components.
The prior art recognizes that occasionally, light is not produced or, if produced, light is not produced at the desired maximum intensity level, when the first and second components are mixed, even after a prolonged induction period. Such failures are known to occur, even when the fluorescer is present in the first component and the catalyst is present in the second component.
The failure associated with no, or low-level, light production has been traced to an unexplained fault in the oxalate component. Studies have shown that the oxalate component is extremely sensitive to the presence of trace quantities of moisture and by-products remaining with the oxalate after its synthesis, notwithstanding that rigorous efforts are taken during the synthesis of the oxalate component (e.g. an environment of dry argon, purification of reactants and solvents, control of reaction time and temperature, repeated distillation/re-crystallization of the oxalate product, etc.). Therefore, it is desirable to have a process which will quickly and inexpensively insure that the oxalate component may be purified such that the oxalate component will never fail to produce the maximum possible luminosity intensity promptly upon mixing of the first and second components.
U.S. Pat. No. 3,948,797 describes a process for overcoming the oxalate component failure which involves treating the oxalate component at room temperature with an alkali-metal alumino-silicate, i.e. a solid molecular sieve material, e.g. Linde Molecular Sieves--Type 5A or the like. However, this process has several drawbacks: firstly and most importantly, such treatment is not successful in every case; secondly, alkali-metal alumino-silicates are expensive materials; thirdly, treatment times are of the order of several hours and a period of about 16 hours of standing is required before the oxalate component may be decanted from the alkali-metal alumino-silicate.
U.S. Pat. No. 4,017,415 recognizes the drawbacks of the process of the '797 patent and substitutes anhydrous activated alumina for the alkali-metal alumino-silicate. However, anhydrous activated alumina is expensive and the treatment involves a relatively high level of alumina. Moreover, separation of the oxalate component from the alumina entails the use of laborious, time-consuming and expensive filtration methods.